Emulsions and methods of making emulsions

ABSTRACT

Disclosed are methods for making emulsions and emulsions, that in some embodiments can be considered to be Pickering emulsions.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/345,386 filed on Mar. 17, 2014, which is a National Phase of PCTPatent Application No. PCT/IB2012/055004 having International FilingDate of Sep. 20, 2012, which claims the benefit of priority of U.S.Provisional Patent Application No. 61/537,799 filed on Sep. 22, 2011.The contents of the above applications are all incorporated by referenceas if fully set forth herein in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The invention, in some embodiments, relates to the field of emulsions.

An emulsion is a mixture of at least two normally-immiscible liquids. Inan emulsion, at least one liquid, constituting the dispersed phase, ispresent as a plurality of discrete droplets dispersed in at least onesecond liquid, constituting the continuous phase.

Typically, emulsifiers are added to an emulsion. Emulsifiers arematerials that are soluble in one of the liquids of the emulsion topromote formation and stability of an emulsion. The nature of a specificemulsifier or combination of emulsifiers also assists in determiningwhether a given mixture will be a water-in-oil (aqueous dispersed phase)or oil-in-water emulsion (non-aqueous dispersed phase).

One specific type of emulsion is the Pickering emulsion. In a Pickeringemulsion, the emulsion includes a shell of solid particles located atthe interfaces between the dispersed phase droplets and the continuousphase. Pickering emulsions are typically made by combining an oil, awater and solid particles (typically less than 100 micrometers indiameter) and then vigorously mixing, for example in a blender.Depending on the relative amounts of the water and oil, the size of thesolid particles and the nature of the solid particles (generally thephase that preferentially wets the particle will be the continuousphase), a water-in-oil or oil-in-water Pickering emulsion is formed,where the presence of the solid particles increases stability of theemulsion by preventing the dispersed phase droplets from coalescing.

SUMMARY OF THE INVENTION

The invention, in some embodiments, relates to methods for makingemulsions having a dispersed phase comprising liquid marbles,substantially Pickering emulsions. The invention, in some embodiments,relates to emulsions having a dispersed phase comprising liquid marbles.

Some aspects of the invention have been published as a scientificarticle in the Journal of Colloid and Interface Science 2012, 366, pp.196-199 available online on Sep. 24, 2011, which is included byreference as if fully set-forth herein.

According to an aspect of some embodiments of the invention, there isprovided a method of making an emulsion comprising a dispersed phase ina continuous phase, comprising:

-   -   a. providing two liquids,        -   i. a first liquid intended as a continuous phase of the            emulsion, and        -   ii. a second liquid intended as a component of a dispersed            phase of the emulsion;    -   b. providing a plurality of liquid marbles, the liquid marbles        comprising a droplet of the second liquid covered with a shell        of particles;    -   c. subsequent to b, immersing the plurality of liquid marbles in        the first liquid,        thereby making the emulsion wherein the plurality of liquid        marbles constitute at least a portion of a dispersed phase of        the emulsion and the first liquid constitutes a continuous phase        of the emulsion.

In some embodiments, the providing a plurality of liquid marblescomprises:

making the liquid marbles by,

-   -   placing the particles on a surface;    -   setting droplets of the second liquid on the surface; and    -   allowing the set droplets to roll on the surface so as to be        covered by the particles, thereby forming the liquid marbles.

In some embodiments, the providing of the plurality of liquid marblescomprises:

making liquid marbles comprising a droplet of the second liquid coveredwith a shell of the particles;

prior to the immersing the liquid marbles in the first liquid, selectingonly a portion of the made marbles for the immersion;

immersing the selected the made marbles in the first liquid; and

not immersing the not selected the made marbles in the first liquid.

In some embodiments, the method further comprises:

d. providing a third liquid intended as a component of a dispersed phasein addition to the dispersed phase of the liquid marbles comprising adroplet of the second liquid;

e. providing a plurality of liquid marbles, each the liquid marblecomprising a droplet of the third liquid covered with a shell ofparticles;

f. subsequent to e, immersing the plurality of liquid marbles comprisinga droplet of the third liquid in the first liquid,

thereby making the emulsion wherein:

the plurality of liquid marbles comprising a droplet of the secondliquid constitute a portion of a dispersed phase of the emulsion;

the plurality of liquid marbles comprising a droplet of the third liquidconstitute a portion of a dispersed phase of the emulsion; and

the first liquid constitutes a continuous phase of the emulsion.

According to an aspect of some embodiments of the invention, there isalso provided an emulsion, comprising:

a continuous phase of a first liquid; and

a dispersed phase comprising a plurality liquid marbles, the liquidmarbles comprising a droplet of a liquid covered with a shell ofparticles,

wherein at least one of:

-   -   a size distribution of the dispersed phase is a non-probability        distribution;    -   the dispersed phase includes at least two distinct particle        populations;    -   the dispersed phase includes at least one distinct population of        the liquid marbles which droplet of liquid is miscible with the        first liquid of the continuous phase;    -   the dispersed phase includes at least one distinct population of        the liquid marbles which droplet of liquid comprises a        non-soluble constituent suspended therein;    -   the dispersed phase includes at least one distinct population of        the liquid marbles which droplet of liquid is substantially        different from and miscible with the first liquid of the        continuous phase;    -   the dispersed phase includes at least one distinct population of        the liquid marbles having an average diameter of not less than        100 micrometers;    -   the dispersed phase includes at least one distinct population of        the liquid marbles which shell of particles is a mixture of at        least two different materials;    -   the dispersed phase includes at least one distinct population of        the liquid marbles which shell of particles has an average        dimension of not less than 10 micrometers; and    -   the emulsion comprising at least two components that tend to        chemically react when in contact under normal conditions, the at        least two components mutually isolated from such contact by        virtue of isolation of at least one of the components in a the        liquid marble.

According to an aspect of some embodiments of the invention, there isalso provided an emulsion comprising:

a continuous phase including at least one oil; and

a dispersed phase including liquid marbles, the liquid marblescomprising:

-   -   droplets of a liquid selected from the group consisting of        water, water solutions, glycerol, and glycerol solutions; and    -   covering the surface of the droplets, a shell of particles        substantially insoluble in the continuous phase and in the        droplets of liquid.

According to an aspect of some embodiments of the invention, there isalso provided a method of making an emulsion comprising:

-   -   a) providing a liquid including at least one oil;    -   b) providing a liquid marble of a droplet of a liquid selected        from the group consisting of water, water solutions, glycerol        and glycerol solutions which surface is covered with a shell of        particles substantially insoluble in the droplet of liquid and        in the liquid including at least one oil;    -   c) subsequent to b, immersing the liquid marble in the liquid        including at least one oil thereby making the emulsion wherein        the liquid marble constitutes a dispersed phase and the liquid        including at least one oil constitutes a continuous phase.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which the invention pertains. In case of conflict, thespecification, including definitions, will take precedence.

As used herein, the terms “comprising”, “including”, “having” andgrammatical variants thereof are to be taken as specifying the statedfeatures, integers, steps or components but do not preclude the additionof one or more additional features, integers, steps, components orgroups thereof. These terms encompass the terms “consisting of” and“consisting essentially of”.

As used herein, the indefinite articles “a” and “an” mean “at least one”or “one or more” unless the context clearly dictates otherwise.

As used herein, when a numerical value is preceded by the term “about”the term “about” is intended to indicate +/−10%.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Some embodiments of the invention are described herein with reference tothe accompanying figure. The description, together with the figure,makes apparent to a person having ordinary skill in the art how someembodiments of the invention may be practiced. The figure is for thepurpose of illustrative discussion and no attempt is made to showstructural details of an embodiment in more detail than is necessary fora fundamental understanding of the invention. For the sake of clarity,some objects depicted in the figure are not to scale.

In the Figures:

FIG. 1 is a reproduction of a photograph of liquid marbles comprising adroplet of water, (left side, with a shell of PVDF particles; rightside, with a shell of lycopodium powder particles) resting on asuperhydrophobic surface;

FIGS. 2A-2B are a reproduction of a photograph of an emulsion of liquidmarbles comprising a droplet of water with a shell of lycopodium powderparticles immersed in a polydimethylsiloxane (PDMS) continuous phase;

FIG. 3 is a reproduction of a photograph of an emulsion of liquidmarbles comprising a droplet of water with a shell of lycopodium powderparticles immersed in a 1,2-dichloroethane continuous phase; and

FIG. 4 is a reproduction of a photograph of an emulsion of liquidmarbles comprising a droplet of water with a shell of PVDF particlesimmersed in a CCl₄ continuous phase.

DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

The invention, in some embodiments, relates to methods for makingemulsions having a dispersed phase comprising liquid marbles,substantially Pickering emulsions. The invention, in some embodiments,relates to emulsions having a dispersed phase comprising liquid marbles.

As known in the art, in a Pickering emulsion solid particles are locatedin the interfaces between the dispersed phase droplets and thecontinuous phase [36]. Apparently, the presence of the solid particlesincreases stability of the emulsion by preventing the dispersed phasedroplets from coalescing.

Liquid marbles [1-35, 37-40] comprise a droplet of water and the like(e.g., water solutions, glycerol, glycerol solutions, ionic liquids [8]the outer surface of which is completely covered by a shell of solidparticles (hydrophobic or hydrophilic particles). When such a liquidmarble rests on a solid or liquid surface, the marble and surface areseparated by gas (e.g., air or vapor) trapped in the rough surface ofthe particles of the shell forming a gas layer similarly to aLeidenfrost droplet [1, 2, 20]. As a result of this gas layer interface,liquid marbles exhibit extremely low friction [1, 2, 39]. The practicaluse of marbles is limited by the fact that the shell is gas-permeable sothat the liquid making up the core evaporates at ambient conditions.[11, 35]

Herein are disclosed methods of making emulsions having a dispersedphase comprising liquid marbles. In some embodiments, such emulsions canbe considered as a type of Pickering emulsion due to the presence of adispersed phase including a shell of solid particles. In someembodiments, the emulsions are devoid of an emulsifier. Typically, anemulsion according to the teachings herein comprises a large pluralityof liquid marbles, e.g., not less than 5, not less than 10, not lessthan 100 and even not less than 1000 marbles.

Method of Making an Emulsion

According to an aspect of some embodiments of the teachings herein,there is provided a method of making an emulsion comprising a dispersedphase in a continuous phase, comprising:

-   -   a. providing two liquids,        -   i. a first liquid intended as a continuous phase of the            emulsion, and        -   ii. a second liquid intended as a component of a dispersed            phase of the emulsion;    -   b. providing a plurality of liquid marbles, the liquid marbles        comprising a droplet of the second liquid covered with a shell        of particles;    -   c. subsequent to b, immersing the plurality of liquid marbles in        the first liquid        thereby making the emulsion wherein the plurality of liquid        marbles constitute at least a portion of a dispersed phase of        the emulsion and the first liquid constitutes a continuous phase        of the emulsion.

As is clear to a person having ordinary skill in the art upon perusal ofthe description herein, the teachings herein allow making emulsionshaving specific selected rheological and other desirable properties,with the use of few or no additives such as emulsifiers and/orsurfactants and/or cosolvents.

Thus according to an aspect of some embodiments of the teachingstherein, there is provided and emulsion comprising a continuous phase ofa first liquid; and a dispersed phase comprising a plurality liquidmarbles, the liquid marbles comprising a droplet of a liquid coveredwith a shell of particles.

Providing Liquid Marbles

The liquid marbles can be provided in any suitable way. In someembodiments, the liquid marbled are made, e.g., using any suitablemethod. For example, in some embodiments, the liquid marbles are madeby: forming a droplet of the second liquid; and coating the surface ofthe droplet with the particles, thereby forming the shell of particles.In some such embodiments, a liquid marble is made by: providing a layerof the particles on a surface; depositing a droplet of the second liquidon the layer of particles (e.g., using a pipette, for example, a meteredpipette); and moving the droplet of the second liquid on the layer ofparticles (e.g., by tilting the surface, applying a fluid flow such as agas flow to roll the particles on the layer of particles and/or thesurface is tilted when the droplet is applied) so as to coat the surfaceof the droplet with the particles, thereby forming the liquid marble.

Thus, in some embodiments, the providing a plurality of liquid marblescomprises:

making the liquid marbles by:

-   -   placing the particles on a surface;    -   setting droplets of the second liquid on the surface; and    -   allowing the set droplets to roll on the surface so as to be        covered by the particles, thereby forming the liquid marbles.

Placing Particles

The particles are placed on the surface in any suitable fashion, forexample by spreading, dropping, sowing or otherwise dispensing theparticles on the surface. In some embodiments, the particles are placedon the surface, a batch of marbles is formed, and when necessary, moreparticles are placed to replenish the amount of particles on thesurface. In some embodiments, the placing of the particles on thesurface is substantially continuous or intermittent.

Rolling

Rolling of the droplets is achieved in any suitable way. In someembodiments, the surface is sloped: the droplets are set on the surfaceand roll down the surface as a result of the slope. In some embodiments,the slope is fixed. In some embodiments, the surface is tiltableallowing the degree and direction of the slope to be changed.

Complete Layer of Particles

In some embodiments, the particles are placed on the surface to form acomplete layer so that the underlying surface is not apparent. In somesuch embodiments, the nature of the underlying surface is typically ofrelative little significance and can be any suitable surface, typicallysmooth so that the layer of particles placed thereupon is uniform. Insuch embodiments, droplets of liquid roll on a layer of particles. Somesuch embodiments have a number of disadvantages, including: theresistance to rolling, especially for small particles, may be too great;generating and maintaining the layer of particles to be suitable forrolling of droplets may be challenging; a rolling droplet may causefurrows or dips to form in the layer of particle, so the droplet, orsucceeding droplets may not successfully roll.

Sparse Layer of Particles

In some embodiments, the particles are placed on the surface sparsely,that is to say, that at least some of the surface is apparent throughthe layer of particles thereupon. The surface can be any suitablesurface, and is typically smooth so that the droplets roll easily on thesurface. In such embodiments, a rolling droplet contacts both particlesand the surface. In some such embodiments, to assist in ensuringrolling, avoid spreading of the droplet on the surface or adhesion ofthe droplet to the surface that potentially slows the rolling, thesurface has a low wettability by the second liquid that makes up thedroplets.

Wettability of the Surface

In some embodiments, the surface has a low wettability by the secondliquid.

If a droplet of the second liquid contacts a portion of a surface havinga low wettability by the second liquid, the droplet does not spread oradhere to the surface but rolls along the surface. Low wettability helpsensure that the droplets roll quickly and do not collide to coalesce.Importantly, such low wettability allows the layer of particles to be assparse as desired to assist in ensuring that the droplets can easily andquickly roll on the surface.

The degree of wettability of a surface of a material by a liquid istypical expressed by the contact angle at a material/liquid interface. Amaterial having a contact angle of less than or equal to 90° isconsidered wettable while a contact angle of greater than 90° isconsidered of low wettability. When the contact angle of water to asurface is greater than 90° the surface is considered hydrophobic, andwhen the contact angle of water to a surface is greater than 140° thesurface is considered superhydrophobic. When the contact angle of awater-immiscible liquid to a surface is greater than 90° the surface isconsidered oleoophobic to that liquid, and when the contact angle of thewater immiscible liquid to a surface is greater than 140° the surface isconsidered superoleophobic to that liquid.

It is generally accepted that there are two types of contact angles:Young equilibrium contact angle and apparent contact angle.

The Young equilibrium contact angle can be established for any materialfor which a flat, smooth, non-deformable, homogeneous chemicallynon-active surface can be fashioned. Specifically, a drop of liquid isplaced on such a surface and the Young contact angle measured, forexample using a goniometer.

For powders, chemically heterogeneous surfaces, or rough (i.e., havingnanoscale or larger features, in some cases leading to the Lotus effect)surfaces, the Young contact angle cannot be measured, and instead, theapparent contact angle is measured. The apparent contact angle isdefined as the angle between the tangent to the liquid-film interfaceand the apparent solid surface as macroscopically observed. For powders,apparent contact angle is often measured by placing a drop of liquid ona flat adhesive surface (e.g., sticky tape) covered with the powder (seeMarmur A “A guide to the equilibrium contact angles maze” in ContactAngle Wettability and Adhesion, V. 6, pp. 3-18, ed. by K. L. Mittal,VSP, Leiden, 2009).

It has been found that in some embodiments, the less the wettability ofthe surface by the second liquid, the more satisfactory the process ofcovering the droplets of the second liquid with a shell of particles.

Accordingly, in some embodiments, the second liquid has a contact angle(Young equilibrium contact angle or apparent contact angle, whicheverrelevant) of not less than 100° not less than 110°, not less than 120°and even not less than 130° with the surface. In such embodiments, ifthe second liquid is water-miscible the surface is hydrophobic and ifthe second liquid is water-immiscible the surface is oleophobic.

In some embodiments, the second liquid has a contact angle (Youngequilibrium contact angle or apparent contact angle, whichever relevant)of not less than 140°, not less than 150° and even not less than 160°with the surface. In such embodiments, if the second liquid iswater-miscible the surface is superhydrophobic and if the second liquidis water-immiscible the surface is superoleophobic.

Setting of the Droplets

The droplets of the second liquid are set on the surface and/or on topof the layer of particles in any suitable fashion.

In some embodiments, the setting of the droplets comprises:

generating droplets of the second liquid; and

placing the generated droplets on the surface.

In some embodiments, generated droplets are directed at the surface. Insome embodiments, the droplets are allowed to settle on the surfaceand/or on top of the layer of particles.

The droplets can be generated in any suitable fashion using any suitablecomponent. Depending on the embodiment, suitable components forgenerating droplets to implement the teachings herein include sprayers(having any suitable spray nozzle), aerosol sprayers, atomizers(including, but not limited to rotary and ultrasonic atomizers),nebulizers, electrosprays, thermosprays, vibrating orifice aerosolgenerators, pipettes and droppers.

Nature of the Liquids

The first and second liquids are any suitable pair of liquids, typically(though not necessarily) two different liquids.

Mutually Immiscible Liquids

In the art, it is know that emulsions, including Pickering emulsions,comprise two mutually-immiscible liquids, a first liquid thatconstitutes a continuous phase of the emulsion, and a second liquid thatconstitutes a dispersed phase of the emulsion. When the continuous phaseis miscible with water and the dispersed phase is immiscible with water,the emulsion is an oil-in water emulsion. When the continuous phase isimmiscible with water and the dispersed phase is miscible with water,the emulsion is a water-in-oil emulsion.

Similarly, in some embodiments, the first liquid and the second liquidare mutually immiscible. In some embodiments, one of the first andsecond liquids is water-miscible and another is water-immiscible. Insome embodiments, the first liquid is immiscible in water and the secondliquid is miscible in water, so that the emulsion is a water-in-oilemulsion. In some embodiments, the first liquid is miscible in water andthe second liquid is immiscible in water, so that the emulsion is anoil-in-water emulsion.

Mutually Miscible Liquids

Despite the above, since in the method of making emulsions according tothe teachings herein liquid marbles making up the dispersed phase arefirst provided and only subsequently immersed in the continuous phase,in some embodiments, the first liquid and the second liquid are mutuallymiscible.

In some embodiments, the first liquid and the second liquid are mutuallymiscible. In some embodiments, the first liquid and the second liquidare different and mutually miscible. In some embodiments, the first andthe second liquid are both water-miscible. In some embodiments, thefirst and the second liquid are both water-immiscible.

Water-Miscible Liquids

In some embodiments, at least one of the first liquid and the secondliquid is a water-miscible liquid. In some embodiments, at least one ofthe first liquid and the second liquid is a water miscible liquidcomprising a single (typically substantially pure) water-misciblematerial. In some embodiments, at least one of the first liquid and thesecond liquid is a water miscible liquid comprising a mixture of atleast two different materials. In some embodiments, at least one of thefirst liquid and the second liquid is an acidic water miscible liquidhaving a pH not greater than 6, not greater than 5 and even not greaterthan 4. In some embodiments, at least one of the first liquid and thesecond liquid is a neutral water miscible liquid having a pH between 6and 8 (inclusive). In some embodiments, at least one of the first liquidand the second liquid is a basic water miscible liquid having a pH notless than 8, not less than 9 and even not less than 10.

In some embodiments, at least one of the first liquid and the secondliquid is a water-miscible liquid selected from the group consisting ofwater, water solutions, glycerol and glycerol solutions.

In some embodiments, at least one of the first liquid and the secondliquid is a water-miscible liquid comprising at least one water-solubleconstituent dissolved in the water-miscible liquid. For example, in somesuch embodiments, a water-soluble constituent is an activepharmaceutical ingredient.

Water-Immiscible Liquids

In some embodiments, an emulsion according to the teachings hereincomprises a liquid including at least one oil. As used herein, the term“oil” refers to a liquid that is substantially insoluble and immisciblein water.

In some embodiments, at least one of the first liquid and the secondliquid is a water-immiscible liquid comprising at least one oil, in someembodiments, a mixture of at least two oils.

In some embodiments, the water-immiscible liquid comprises at least onematerial selected from the group consisting of non-polar oils, petroleumether, toluene, xylene (e.g., ortho-, meta-, para-isomers and mixturesthereof), carbon tetrachloride (CCl₄), dichloromethane,1,2-dichloroethane, chloroform, silicone oils (polyalkyl siloxane (suchas cyclomethicone and/or dimethicone), polyaryl siloxane, polyalkylarylsiloxane, polyether siloxane copolymer, and combinations thereof, e.g.,polydimethylsiloxane such as Sylgard 184 and Dow Corning 2000), edibleoils. vegetable oils (sunflower, rapeseed, olive, peanut, coconut, soy),animal oils and mixtures thereof.

In some embodiments, at least one of the first liquid and the secondliquid is a water-immiscible liquid comprising at least onewater-insoluble constituent dissolved in the water-immiscible liquid.For example, in some such embodiments, a water-insoluble constituent isan active pharmaceutical ingredient.

Non-Soluble Constituent

Since in the method of making emulsions according to the teachingsherein liquid marbles making up the dispersed phase are first providedand only subsequently immersed in the continuous phase, in someembodiments, the second liquid making up the droplet of a liquid marblecomprises a non-soluble constituent suspended in the second liquid. Forexample, in some embodiments, such a non-soluble constituent is anon-soluble solid (e.g., of TiO₂) and the second liquid is a watersuspension or sol. For example, in some embodiments, such a non-solubleconstituent is a non-soluble liquid and the liquid marbles comprisedroplets of a suspension or a colloid where covering the surface of thedroplets is a shell of the particles.

Accordingly, in some embodiments, the second liquid comprises anon-soluble constituent suspended therein. In some such embodiments, thesecond liquid is selected from the group consisting of a colloid, anemulsion, water-in-oil emulsion, oil-in-water emulsion, a sol (soliddispersed phase in a liquid continuous phase), a hydrocolloid(hydrophilic polymers in water) and a suspension (solid particlesdispersed in a liquid continuous phase that do eventually settle)

Droplet Size

The size of the droplets of the second liquid making up the liquidmarbles of an emulsion according to the teachings herein is any suitablesize.

In some embodiments, the droplets have an average diameter of not lessthan 50 nm, not less than 75 nm and even not less than 100 nm.

In some embodiments, the droplets have an average diameter of not morethan 10 mm, not more than 5 mm, not more than 4 mm, not more than 3 mm,not more than 2 mm and even not more than 1 mm.

In this context, it is important to note that in known Pickeringemulsions, the droplets have an average diameter of not greater than 100micrometers, while in some embodiments of the emulsions according to theteachings herein, the droplets are larger. Specifically, in someembodiments, the droplets have an average diameter of not less than 100micrometers, not less than 200 micrometers, not less than 500micrometers and even not less than 1 mm.

Particles Constituting the Shell of the Liquid Marbles

Like in all Pickering emulsions, the shell of particles covering thedroplets of the second liquid according to the teachings herein areadsorbed onto the interface between the two phases. It is generallyaccepted that the shell of particles stabilizes a Pickering emulsion bypreventing contact between the liquid in any two droplets, preventingdroplet coalescence and eventual phase-separation.

Any suitable particle or mixture of particles can be used inimplementing the teachings herein, especially any suitable particleknown in the art to be suitable for use in implementing a Pickeringemulsion.

In some embodiments, the particles are solid particles. In someembodiments, the particles are substantially insoluble in the firstliquid and in the second liquid.

Wettability of Particles

In known Pickering emulsions the particles covering the dispersed phasedroplets are preferentially wettable by the liquid of the continuousphase rather than the liquid of the dispersed phase. In known Pickeringemulsions, the nature of the solid particles often determines whetherthe emulsion is a water-in-oil or oil-in-water emulsion. Specifically,hydrophobic particles (not wettable by water) stabilize water-in-oilemulsions, whereas hydrophilic particles (wettable by water) stabilizeoil-in-water emulsions.

Accordingly, in some embodiments, the particles are more wettable by thefirst liquid (intended to be the continuous phase) than by the secondliquid (intended to be the dispersed phase). That said, since in themethod of making emulsions described herein liquid marbles making up thedispersed phase are first provided and only subsequently immersed in thecontinuous phase, in some embodiments the particles are more wettable bythe second liquid (intended to be the dispersed phase) than by the firstliquid (intended to be the continuous phase).

In some embodiments, the second liquid has an apparent contact angle ofnot less than 100°, not less than 110°, not less than 120° and even notless than 130° with the surface. In such embodiments, if the secondliquid is water-miscible the particles are hydrophobic, and if thesecond liquid is water-immiscible the particles are oleophobic.

In some embodiments, the second liquid has an apparent contact angle ofnot less than 140°, not less than 150° and even not less than 160° withthe surface. In such embodiments, if the second liquid is water-misciblethe particles are superhydrophobic, and if the second liquid iswater-immiscible the particles are superoleophobic.

Particles Material

In some embodiments, the particles placed on the surface as describedabove are all of a single material, so that the particles of a shell ofa given individual marble are substantially all of a single material.

That said, in some embodiments, particles of at least two differentmaterials are simultaneously placed on the surface as described above,so that the particles of a shell of a given individual marble are amixture of at least two different materials.

In some embodiments, the particles comprise particles selected from thegroup consisting of polyethylene (PE), polypropylene (PP),polytetrafluoroethylene (PTFE), silica (colloidal silica, fumed silica),carbon black, adsorbed polyelectrolytes (poly(sodium styrene sulfonate)PSS; polyacrylic acid (PAA); poly[N-(3-aminopropyl)methacrylamide(APMA); polyethyleneamine (PEA); polyvinylidene difluoride (PVDF);polypeptides (e.g., proteins such as casein, poly-arginine, corn proteinzein); polysaccharides (e.g., pectin, chitosan, cellulose); lechitins;alginates; carrageenan; latex particles, amphiphillic particles (e.g,Janus particles); particulate biological-material (e.g. from abiological source especially as from a botanical source, e.g., pollen,lycopodium powder, seeds, pulverized leaves, stems, bark, such as ofspices and herbs)

Particle Size

Particles of any suitable size or distribution of sizes can be used inimplementing the teachings herein, especially any size or distributionof sizes known in the art to be suitable for use in implementing aPickering emulsion. For example, as known in the art of Pickeringemulsions, in some embodiments the particles are nanoparticles.

In some embodiments, the particles have an average dimension (diameterfor substantially spherical particles, largest dimension for othershapes) of not less than 20 nm, not less than 30 nm, not less than 40 nmand even not less than 50 nm.

In some embodiments, the particles have an average dimension of not morethan 2 mm, not more than 1 mm and even not more than 500 micrometers.

In this context, it is important to note that in known Pickeringemulsions, the particles in the shell of particles have an averagedimension of not greater than 10 micrometers, while in some embodimentsof the emulsions according to the teachings herein, the particles aresubstantially larger. In some embodiments, the particles in the shell ofparticles have an average dimension of not less than 10 micrometers, notless than 20 micrometers and even not less than 50 micrometers.

Dispersed-Phase Size Distribution

As is known to a person having ordinary skill in the art, Pickeringemulsions are made by vigorously mixing a mixture of a first liquid, asecond liquid and particles so that there is a probability distributionof sizes of the dispersed phase particles. Specifically, the dispersedphase is typically found with a Gaussian distribution of droplet sizesdetermined by thermodynamic factors during the mixing step in theformation of the emulsion, what is herein termed a standard orprobability distribution.

Since in the method of making emulsions according to the teachingsherein liquid marbles making up the dispersed phase are first providedand only subsequently immersed in the continuous phase, in someembodiments the distribution of sizes of the liquid marbles constitutingthe dispersed phase particles is a non-probability distribution,allowing selection of rheological properties of the emulsion.

In some embodiments, the dispersed phase of an emulsion as taught hereinhas a non-probability distribution of droplet size. In some embodiments,the dispersed phase of an emulsion as taught herein has a selecteddistribution of droplet size, that is to say, the distribution isspecifically selected when the emulsion is being made.

In some embodiments, the dispersed phase of an emulsion as taught hereinhas a non-standard narrow distribution of droplet sizes. In suchembodiments, the droplet size has a very narrow Gaussian-likedistribution, that is to say a distribution of droplet size determinedby non-thermodynamic factors (e.g., a distribution resulting from theerror of a pipette device used to make the droplets). In someembodiments, the size of the droplets is homogenous, that is to saysubstantially all droplets have a size that is within a specified errorof a median size. In some embodiments, the relative standard error iswithin 5%, within 2%, within 1% and even within 0.5%.

In some embodiments, such emulsions are made by producing liquid marbleshaving a metered size, for example, by depositing metered droplets ofliquid having a specific selected size (within the error of thedepositing device, e.g., pipette) on a surface.

In some embodiments, providing of the plurality of liquid marblescomprises:

making liquid marbles comprising a droplet of the second liquid coveredwith a shell of the particles;

prior to the immersing the liquid marbles in the first liquid, selectingonly a portion of the made marbles for the immersion;

immersing the selected the made marbles in the first liquid; and

not immersing the not selected the made marbles in the first liquid.Selecting can be done according to any suitable method.

In some embodiments, the selecting is according to a predeterminedcriteria. In some embodiments, the predetermined criteria is a size ofthe made liquid marbles, so that:

-   -   some sizes of the made liquid marble are selected for the        immersion and immersed in the first liquid; and    -   some sizes of the made liquid marbles are not selected for        immersion and not immersed in the first liquid. Such selection        of liquid marbles is performed using any suitable method, for        example by sifting or sieving.

Multiple Distinct Dispersed Phase Populations

As is known to a person having ordinary skill in the art, Pickeringemulsions are made by vigorously mixing a mixture of a first liquid, asecond liquid and particles so that the composition of the liquid of allof the droplets of the dispersed phase is the same.

Since in the method of making emulsions according to the teachingsherein liquid marbles making up the dispersed phase are first providedand only subsequently immersed in the continuous phase, in someembodiments the method is used to make an emulsion having a dispersedphase including at least two distinct populations of liquid marbles,where the two distinct populations differ by having, for example,substantially different size distribution and/or substantially differentliquid droplet and/or substantially different particles in the shell ofparticles covering the droplet. For example, in some embodiments anemulsion according to the teaching herein comprises: a first liquidmarble type having a shell of a first type of particle and a secondliquid marble type having a shell of a second type of particle.

In some embodiments, a plurality of liquid marbles (e.g., made asdescribed above) is immersed in an already-made emulsion (e.g., a priorart non-Pickering emulsion, or a prior art Pickering emulsion). In suchembodiments, the “first liquid” is the continuous phase of thealready-made emulsion in which the provided plurality of liquid marblescomprising a droplet of the second liquid are immersed. In otherembodiments, at least two different types of liquid marbles are provided(e.g., independently made, substantially as described above) and aplurality of liquid marbles of each of the at least two different typesare immersed in the first liquid. In an analogous way, in someembodiments the method is used to make an emulsion having a dispersedphase including substantially any practical desired number of distinctpopulations, e.g., at least two distinct populations, at least threedistinct populations of liquid marbles, at least four distinctpopulations, at least five distinct populations of liquid marbles andeven more, each

Thus, in some embodiments, the method further comprises:

-   -   d. providing a third liquid intended as a component of a        dispersed phase in addition to the dispersed phase of the liquid        marbles comprising a droplet of the second liquid;    -   e. providing a plurality of liquid marbles, each the liquid        marble comprising a droplet of the third liquid covered with a        shell of particles;    -   f. subsequent to e, immersing the plurality of liquid marbles        comprising a droplet of the third liquid in the first liquid        thereby making the emulsion wherein:    -   the plurality of liquid marbles comprising a droplet of the        second liquid constitute a portion of a dispersed phase of the        emulsion;    -   the plurality of liquid marbles comprising a droplet of the        third liquid constitute a portion of a dispersed phase of the        emulsion; and    -   the first liquid constitutes a continuous phase of the emulsion.

In some embodiments, the third liquid is different from the firstliquid. In some embodiments, the third liquid is different from thesecond liquid. In some embodiments, the third liquid is miscible withthe first liquid. In some embodiments, the third liquid is miscible withthe second liquid. In some embodiments, the third liquid is immisciblewith the first liquid. In some embodiments, the third liquid isimmiscible with the second liquid.

In some embodiments, the particles making up the shell of particlescovering the droplet of the third liquid are substantially differentfrom the particles making up the shell of particles covering the dropletof the second liquid. Depending on the embodiment, the particles have,for example, a different size distribution and/or a different shapeand/or are of a different material or combination of materials.

In some embodiments, the size distribution of the liquid marblescomprising a droplet of the third liquid is different from the sizedistribution of the liquid marbles comprising a droplet of the secondliquid.

Mutually Reactivity of Emulsion Components

In known emulsions, it is not possible to include mutually-reactivecomponents, during the mixing step, such components contact and react.

In contrast, in some embodiments an emulsion according to the teachingsherein comprises mutually reactive components, that is to say,components that react (e.g., chemically react) if in contact.Accordingly, in some embodiments, the emulsion comprises at least twocomponents that tend to chemically react when in contact under normalconditions, the at least two components mutually isolated from suchcontact, by virtue of isolation of at least one of the componentscomponent in a liquid marble. By normal conditions is meant, forexample, standard temperature and pressure, or conditions in which theemulsion is normally stored.

For example, in some embodiments an emulsion comprises at least twodifferent types of liquid marbles: a first liquid marble type includinga first component dissolved in the respective droplet of liquid and asecond liquid marble type including a second component dissolved in therespective droplet of liquid, where the first component and secondcomponent are mutually reactive, that is to say, would react (e.g.,chemically react) if the liquid of the droplets of the first and secondliquid marble are mixed. In some embodiments, such emulsions are made byforming the two types of liquid marbles separately and subsequentlyimmersing in the same liquid including at least one oil that constitutesthe continuous phase.

Embodiments of Particular Emulsions

As is apparent to a person having ordinary skill in the art, the methodof making an emulsion according to the teachings herein allow makingdifferent types of emulsions, including novel emulsions.

Thus, according to an aspect of some embodiments of the teachingsherein, there is also provided an emulsion comprising:

-   -   a continuous phase of a first liquid; and    -   a dispersed phase comprising a plurality liquid marbles, the        liquid marbles comprising a droplet of a liquid covered with a        shell of particles,        wherein the emulsion is characterized by at least one of:    -   a size distribution of the dispersed phase is a non-probability        (non-standard) distribution, e.g., achieved by selecting made        liquid marbles for immersion according to some predetermined        criteria, as discussed above;    -   the dispersed phase includes at least two distinct particle        populations, e.g., each population characterized by having        different size distribution and/or type of liquid droplet and/or        type of particles making up a respective shell, for example made        by immersing provided liquid marbles in an already-made prior        art emulsion (Pickering or non-Pickering emulsion), or by        immersing at least two distinct types of separately-provided        liquid marbles;    -   the dispersed phase includes at least one distinct population of        liquid marbles which droplet of liquid is miscible with the        first liquid of the continuous phase;    -   the dispersed phase includes at least one distinct population of        liquid marbles which droplet of liquid comprises a non-soluble        constituent suspended therein (e.g., a colloid, an emulsion        (water-in-oil or oil-in-water), a sol (solid dispersed phase in        a liquid continuous phase), a hydrocolloid (hydrophilic polymers        in water), a suspension (solid particles dispersed in a liquid        continuous phase that do eventually settle);    -   the dispersed phase includes at least one distinct population of        liquid marbles which droplet of liquid is substantially        different from and miscible with the first liquid of the        continuous phase;    -   the dispersed phase includes at least one distinct population of        liquid marbles having an average diameter of not less than 100        micrometers, not less than 200 micrometers, not less than 500        micrometers and even not less than 1 mm;    -   the dispersed phase includes at least one distinct population of        liquid marbles which shell of particles is a mixture of at least        two different materials;    -   the dispersed phase includes at least one distinct population of        liquid marbles which shell of particles has an average dimension        of not less than 10 micrometers, not less than 20 micrometers        and even not less than 50 micrometers; and    -   the dispersed phase includes a component that tends to        chemically react with a component of the continuous phase under        normal conditions (for example, standard temperature and        pressure, or conditions in which the emulsion is normally        stored).

EXPERIMENTAL Second Liquids for Liquid Marbles

Triple distilled water was available in the laboratory.

Glycerol (analytical grade) was acquired from Sigma-Aldrich (St. Louis,Mo., USA).

Particles for Marbles

Five types of particles were acquired (Table 1):

TABLE 1 Particle size Type Source (SEM) Ref contact angle Hydrophobicpolytetrafluoroethylene (PTFE) Sigma-Aldrich 150 nm 18 Young 109-112°Apparent 140-160° polyethylene (PE) Sigma-Aldrich 130 nm 37 Young96-102° spectrophotometric grade Apparent 130-150° lycopodium powderFluka 30 μm 38 Young n/a Apparent 140-155° Hydrophilic polyvinylidenefluoride (PVDF) Sigma-Aldrich 130 nm 37 Young 85-89° Apparent 130-155°carbon black (VulcanXC72R) Cabot 30 μm 24 Young 0° 95.92% C, 1.05% S,1.05% O, Apparent 100-130° 0.25% H, and 0.25% N

Liquid Marble Preparation

Liquid marbles comprising water or glycerol droplets having a shell ofthe different particles were prepared as taught in Refs 18-24.Specifically, 20 microliter droplets of water were deposited with amicro-dosing pipette onto a superhydrophobic surface, prepared asdescribed in Ref 37. One of five types of particles was then wassprinkled on the superhydrophobic surface and on the droplets restingthereon. Slight tilting of the superhydrophobic surface caused thedroplets to roll and to be coated with the particles.

In FIG. 1 are depicted water marbles (left side, coated with PVDF, rightside with lycopodium powder).

Oils

Twelve oils, all of analytical grade, were acquired, Table 2:

TABLE 2 Dipole Density Viscosity Oil Source Moment [kg/m2] [Pa/s (25°C.)] Solubility in water Aromatic toluene Frutarom 0.36 D 0.87 0.56 ×10−3 0.47 g/L (20° C.) xylene (mixture of o, m, p) Frutarom o 0.45 D0.88 0.812 × 10−3  o 0.175 g/L (25° C.) m 0.86 0.620 × 10−3  m 0.135 g/L(25° C.) p 0.07 D 0.86 0.34 × 10−3 p 0.198 g/L (25° C.) halogenatedcarbon tetrachloride Biolab 0 1.59  0.9 × 10−3 0.79 g/L (25° C.)dichloromethane Biolab 1.60 D 1.325 0.41 × 10−3 13 g/L (20° C.)1,2-dichloroethane Biolab 1.80 D 1.25 0.78 × 10−3 8.7 g/L (20° C.)chloroform Biolab 1.04 D 1.48 0.54 × 10−3 8. g/L (20° C.) silicone oilSylgard 184 Aldrich n/a 1.03 3.9  insoluble (polydimethylsiloxane, PDMS)Dow Corning 200 Aldrich n/a 0.96 0.34 insoluble (polydimethylsiloxane,PDMS) Polar Oils dimethylsulfoxide (DMSO) Biolab 3.96 D 1.1  2.0 × 10−3miscible N,N,-dimethylformamide Biolab 3.86 D 0.96  0.8 × 10−3 miscible(DMF) acetone Biolab 2.91 D 0.79 0.31 × 10−3 miscible ethanol Biolab1.69 D 0.79  1.1 × 10−3 miscible

Immersion of Liquid Marbles to Form Water-in-Oil Emulsion

Under ambient conditions, each one of the ten different types of marbleswas carefully rolled from the superhydrophobic surface onto the surfaceof each one of the twelve oils held in a vessel.

The behavior of the liquid marbles was monitored with a rapid camera anda Rame-Hart goniometer (Model 500)

Silicone Oils

All ten types of marbles sank to the bottom of the vessel containing oneof the two silicone oils at a velocity dependent on the viscosity of theoil. All ten types of marbles were stable for an unlimited time (atleast one month).

In FIGS. 2A and 2B are depicted water marbles coated with lycopodiumpowder in a PDMS continuous phase. In FIG. 2A are seen three marbleswith 0.01 M KMnO₄ resting on the bottom of a vessel containing PDMS witha fourth marble with pure water sinking. In FIG. 2B are seen manymarbles resting on the bottom of a vessel containing PDMS, somecontaining 0.01 M KMnO₄ and some pure water.

Aromatic Oils

All ten types of marbles sank to the bottom of the vessel containing anaromatic oil at a velocity dependent on the viscosity of the oil.

Liquid marbles coated with lycopodium particles demonstrated excellentstability and remained stable for an unlimited time (at least 1 month).

Liquid marbles coated with PTFE, PVDF, PE and carbon black particlessurvived for several minutes. Liquid marbles with any of the fourpowders burst immediately upon touching the wall of the vessel.

Halogenated Oils

Surprisingly, the liquid marbles did not float on the surface of thehalogenated oils. Instead, the liquid marbles settled to just below thesurface of the halogenated oils.

Liquid marbles coated with lycopodium particles demonstrated excellentstability and remained stable for an unlimited time (at least 1 month).

Liquid marbles coated with PTFE and PVDF particles survived for 5-10minutes, and liquid marbles coated with PE survived for approximately aminute. Marbles with any of the three powders burst immediately upontouching the wall of the vessel.

In FIG. 3 is depicted a lycopodium powder coated water marble just underthe surface of 1,2-dichloroethane.

Polar Oils

Any of the above liquid marbles deposited on the surfaces of acetone,ethanol, DMSO and DMF burst immediately.

The lack of stability of the liquid marbles is attributed to thepolarity of the oil.

Determining the Presence of Air Trapped in the Solid Particle Shell

As known in the art, liquid marbles comprise air trapped in theoutwardly facing surface of the solid particle shell. As a result, aliquid marble resting on a surface has a very low coefficient friction.

It has been reported [20] that liquid marbles of an NaOH solutionfloating on a water/alcohol solution including phenolphthalein do notreact with the phenolphthalein, attributed to the air in the shellpreventing contact therewith.

To determine whether or not air was present on the surface of the liquidmarble dispersed phase of an emulsion as described herein, two types ofliquid marbles were made as taught therein, a first type comprising a0.1M NaOH solution with a shell of PVDF particles and the second typecomprising a 0.1M NaOH solution with a shell of lycopodium powderparticles.

A hydrophobic liquid was made by adding 100 microliter of 0.1%phenolphthalein in ethanol to 100 ml of CCl₄. The marbles were immersedin the hydrophobic liquid. The red color that developed inside theimmersed liquid marbles indicated migration of the phenolphthalein intothe liquid marbles and reaction with the NaOH, indicating that there wasno layer of air in the shell of the liquid marbles. In FIG. 4, aphotograph showing the red color of a liquid marble with a PVDF shell isreproduced.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeature is of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the scope of the appendedclaims.

Citation or identification of any reference in this application shallnot be construed as an admission that such reference is available asprior art to the invention.

The priority document of the application, U.S. Provisional PatentApplication No. 61/537,799 filed 18 Sep. 2011, incorporated by referenceas if fully set-forth herein.

Some aspects of the invention have been published as a scientificarticle in the Journal of Colloid and Interface Science 2012, 366, pp.196-199 available online on Sep. 24, 2011, which is included byreference as if fully set-forth herein.

In case of conflict, the specification, including definitions, will takeprecedence.

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What is claimed is:
 1. A method of making an emulsion having a dispersedphase in a continuous phase, the method comprising: immersing aplurality of liquid marbles in a first liquid intended as the continuousphase of the emulsion, each of said liquid marbles comprising a dropletof a second liquid covered with a shell of particles, wherein saidplurality of liquid marbles comprises one or more type of liquid marble,the method further comprising, prior to said immersing, forming saidliquid marbles by coating said droplet with said particles, to therebyform said shell of particles, wherein said first liquid and said secondliquid are mutually immiscible, said first liquid being immiscible inwater and said second liquid being miscible in water, thereby obtaininga water-in-oil emulsion comprising an immersed plurality of liquidmarbles as at least a portion of said dispersed phase, and said firstliquid in said continuous phase, wherein an average droplet diameter insaid liquid marbles is not less than 50 nm.
 2. The method of claim 1,wherein forming said liquid marbles comprises: placing said particles ona surface; setting droplets of said second liquid on said surface; andallowing said set droplets to roll on said surface so as to be coveredby said particles, thereby forming said liquid marbles.
 3. The method ofclaim 2, wherein said second liquid has an apparent contact angle of notless than 100° with said surface.
 4. The method of claim 1, wherein saidsecond liquid comprises water and/or glycerol.
 5. The method of claim 1,wherein said first liquid comprises at least one substance selected fromthe group consisting of toluene, xylene, carbon tetrachloride,dichloromethane, 1,2-dichloroethane, chloroform, silicone oils, polyarylsiloxane, polyalkylaryl siloxane, polyether siloxane copolymer, andcombinations thereof, edible oils, vegetable oils, animal oils andmixtures thereof.
 6. The method of claim 1, wherein said second liquidincludes a non-soluble constituent suspended therein.
 7. The method ofclaim 6, wherein said second liquid is selected from the groupconsisting of a colloid, an emulsion, oil-in-water emulsion, a sol, ahydrocolloid and a suspension.
 8. The method of claim 1, wherein saiddroplets have an average diameter of not less than 100 μm.
 9. The methodof claim 8, wherein said droplets have an average diameter of not lessthan 1 mm.
 10. The method of claim 1, wherein said droplets have anaverage diameter of not more than 10 mm.
 11. The method of claim 1,wherein said particles are solid particles.
 12. The method of claim 1,wherein said particles comprise a material selected from the groupconsisting of polyethylene, polypropylene, polytetrafluoroethylene,silica, carbon black, poly(sodium styrene sulfonate), polyacrylic acid,poly[N-(3-aminopropyl)methacrylamide, polyvinylidene difluoride,polypeptides, polysaccharides, lecithin, alginate, carrageenan, latex,and lycopodium powder.
 13. The method of claim 1, wherein said particleshave an average dimension of not less than 20 nm.
 14. The method ofclaim 10, wherein said particles have an average dimension of not lessthan 10 μm.
 15. The method of claim 1, wherein said particles have anaverage dimension of not more than 2 mm.
 16. The method of claim 1,comprising: upon said forming said liquid marbles, and prior to saidimmersing of said plurality of liquid marbles, selecting only a portionof formed liquid marbles for immersion, immersing the selected liquidmarbles in said first liquid; and not immersing the non-selected liquidmarbles in said first liquid.
 17. The method of claim 16, wherein saidselecting is according to a predetermined size distribution, so that:some sizes of said made liquid marble are selected for said immersionand immersed in said first liquid; and some sizes of said made liquidmarbles are not selected for immersion and not immersed in said firstliquid.
 18. The method of claim 1, further comprising: immersing anadditional plurality of liquid marbles in said first liquid, each ofsaid liquid marbles in said additional plurality comprising a droplet ofa third liquid covered with a shell of particles, wherein said pluralityof liquid marbles comprises one or more type of liquid marble, such thatsaid emulsion further comprises said additional liquid marbles as aportion of said dispersed phase.
 19. The method of claim 18, whereinsaid particles of said droplet of said third liquid differ from saidparticles of said droplet of said second liquid, and/or a sizedistribution of said liquid marbles comprising said droplet of saidthird liquid differs from a size distribution of said liquid marblescomprising said droplet of said second liquid.
 20. An emulsion,comprising: a continuous phase of a first liquid; and a dispersed phasecomprising a plurality of liquid marbles, said plurality of liquidmarbles comprising one or more type of liquid marble, said liquidmarbles comprising a droplet of a liquid covered with a shell ofparticles, wherein at least one of: said first liquid constituting saidcontinuous phase includes a non-soluble constituent suspended therein; asize distribution of said dispersed phase is a non-probabilitydistribution; said dispersed phase includes at least two distinctpopulations of said liquid marbles; said dispersed phase includes atleast one distinct population of said liquid marbles which droplet ofliquid is miscible with said first liquid of said continuous phase; saiddispersed phase includes at least one distinct population of said liquidmarbles which droplet of liquid is substantially different from andmiscible with said first liquid of said continuous phase; said dispersedphase includes at least one distinct population of said liquid marbleswhich droplet of liquid comprises a non-soluble constituent suspendedtherein; the emulsion comprising at least two components that tend tochemically react when in contact under normal conditions, said at leasttwo components mutually isolated from such contact by virtue ofisolation of at least one of said components in a said liquid marble.